package com.android.data;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
  
public class DatabaseHelper extends SQLiteOpenHelper {

	//The Android's default system path of your application database "/data/data/YOUR_PACKAGE/databases/";
    private static String DB_PATH = "/data/data/com.android/databases/";
    private static String DB_NAME = "schedulerdb";
    
    private SQLiteDatabase myDataBase; 
	private Context myContext;
	
    /**
     * Constructor
     * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
     * @param context
     */
    public DatabaseHelper(Context context) {
    	super(context, DB_NAME, null, 1);
        this.myContext = context;
    }	
 
    /**
     * Creates a empty database on the system and rewrites it with your own database.
     **/
    public boolean createDataBase() throws IOException{
    	boolean dbExist = checkDataBase();
    	boolean result = false;
    	
    	// force creation of database
    	dbExist = false;
    	
    	if(dbExist){
    		//do nothing - database already exist
    	
    	} else {

        	// Path to the just created empty db
        	// String outFileName = DB_PATH + DB_NAME;
    		// erase old file
    		// Runtime.getRuntime().exec("rm " + outFileName);
    		
    		
    		//By calling this method an empty database will be created into the default system path
            //of your application so we are gonna be able to overwrite that database with our database.
        	this.getWritableDatabase();
        	
        	try { 
    			copyDataBase();
    			Log.i("database", "Sucesso ao copiar banco de dados.");
    			result = true;
    			
    		} catch (IOException e) {
    			Log.e("error", e.getMessage());
        		throw new Error("Error copying database");
    			//android.util.Log.e("Error", "Error copying database.");
        	}
    	}
    	
    	return result;
    }
 
    /**
     * Check if the database already exist to avoid re-copying the file each time you open the application.
     * @return true if it exists, false if it doesn't
     */
    private boolean checkDataBase(){
    	SQLiteDatabase checkDB = null;
 
    	try{
    		//Check if the database exists
    		File databaseDir = myContext.getDir("databases", Context.MODE_PRIVATE);
    		Log.i("databaseDir", databaseDir.toString());
    		File[] list = databaseDir.listFiles();
    		
    		for (int i = 0; i < list.length; i++) {
    			if (list[i].equals(DB_NAME)) {
    				android.util.Log.i("DBpath", DB_PATH);
    				checkDB = SQLiteDatabase.openDatabase(DB_PATH, null, SQLiteDatabase.OPEN_READWRITE);
    			}
    		}
    		 
    	} catch(SQLiteException e) {
    		android.util.Log.e("Database", "There's no database yet.");
    		
    	}
 
    	if(checkDB != null){
    		checkDB.close();
    	}
 
    	return checkDB != null ? true : false;
    }
 
    /**
     * Copies your database from your local assets-folder to the just created empty database in the
     * system folder, from where it can be accessed and handled.
     * This is done by transfering bytestream.
     * */
    private void copyDataBase() throws IOException{
    	//Open your local db as the input stream
    	InputStream myInput = myContext.getAssets().open(DB_NAME);
 
    	// Path to the just created empty db
    	String outFileName = DB_PATH + DB_NAME;

    	//Open the empty db as the output stream
    	OutputStream myOutput = new FileOutputStream(outFileName);
 
    	//transfer bytes from the inputfile to the outputfile
    	byte[] buffer = new byte[1024];
    	int length;
    	while ((length = myInput.read(buffer)) != -1) {
    		myOutput.write(buffer, 0, length);
    	}
    	
		//Changing file privileges
		Runtime.getRuntime().exec("chmod 777 " + outFileName);

    	//Close the streams
    	myOutput.flush();
    	myOutput.close();
    	myInput.close();
 
    }
 
    public void openDataBase() throws SQLException{
    	myDataBase = SQLiteDatabase.openDatabase(DB_PATH, null, SQLiteDatabase.OPEN_READWRITE);
    }
 
    @Override
	public synchronized void close() {
    	if(myDataBase != null)
    		myDataBase.close();
    	super.close();
	}
 
	@Override
	public void onCreate(SQLiteDatabase db) {
	}
 
	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
 
	}
 
}
